Belt alignment system with rotatable bushing

ABSTRACT

An alignment system for a conveyor having a conveyor belt trained over rollers on a conveyor frame, is provided and includes pivoting members each mounted on a corresponding support bracket, the pivoting members configured for supporting tracking rollers at corresponding tracking roller shaft ends, each shaft end pivotally and non-rotatably attached to corresponding pivoting members by a rotating bushing mounted in a corresponding pivoting member; and a guide control bar having two ends being pivotally connected at each end to a corresponding torque arm connected to the corresponding pivoting member. The bar includes guide rollers positioned at both edges of the conveyor belt for lateral control of the belt.

BACKGROUND

The present invention relates to the operation of conveyor belts, suchas those known as endless belts supported by a series of parallelsupport rollers, and more particularly to a system for maintainingalignment of a conveyor belt during operation.

Belt tracking is a problem in any industry that uses conveyor belts. Itis often not a major problem but rather a maintenance nuisance thatprogressively over time becomes a major cost.

Several factors can affect belt tracking. Misalignment of the rollerswill cause corresponding belt tracking problems. Also, uneven loading ofconveyor belts may also cause tracking problems, as well as unequaldriving forces across the belt width.

Further, it is common for a tracking device for conveyor belts to failprematurely. Carry back material (material that has not been removed bya belt scraper at the conveyor discharge point) for instance may causematerial build up and result in the rollers and pivot mechanism to seizeinto a misalignment position.

Various conveyor belt systems have been developed over the years withdesign considerations relating to accurate tracking. Within any belt theability to track will vary considerably, and this in turn is due to anumber of variables involved in the production of a belt itself.Compounding this problem is the possibility that the belt might bestretched upon installation. Over correction during initial trackingadjustments may result in stretching the belt in inappropriate areas. Ithas also been observed that existing tracking devices will only align aconveyor belt once it is way off center, thereby resulting in seriousdamage and down time.

In U.S. Pat. No. 7,051,867, which is incorporated by reference, asuitable belt alignment system includes a pair of pivoting members, eachmounted on a corresponding support bracket. Each pivoting member isconfigured for supporting one of a pair of tracking rollers at acorresponding tracking roller shaft end. Each shaft end is pivotally andnon-rotatably attached to a corresponding pivot member by a ball bushingmounted in a corresponding one of the pivot members.

In some applications, it has been found that the configuration of theball bushing has a relatively limited travel distance that impedes therequired range of adjustment for proper conveyor belt alignment. Attravel limits of the conventional bushings, the bushings actually“bottom out” before the required degree of alignment movement isachieved. Thus, in some cases, the bushing configuration has become alimiting factor in the effectiveness of the conveyor belt alignmentsystem. It has also been found that conventional ball bushings are proneto corrosion.

SUMMARY OF THE INVENTION

The present belt alignment system addresses the disadvantages of theprior art by providing an improved system featuring a rotatable bushing.In the preferred embodiment an “Oil-Lite” bushing is provided, which ismounted in a block that rotates axially relative to a bushing housing ineach pivoting member. The bushing receives a corresponding shaft end ofthe tracking roller shaft. Suitable lubrication fittings are preferablyprovided on the housing for lubrication of the bushing. It has beenfound that the rotatable block in which the bushing is mounted providesa greater range of rotation compared to prior art units.

More specifically, an alignment system for a conveyor having a conveyorbelt trained over rollers on a conveyor frame is provided and includespivoting members each mounted on a corresponding support bracket, thepivoting members configured for supporting tracking rollers atcorresponding tracking roller shaft ends,

each shaft end pivotally and non-rotatably attached to correspondingpivoting members by a rotating bushing mounted in a correspondingpivoting member. A guide control bar has two ends and is pivotallyconnected at each end to a corresponding torque arm connected to thecorresponding pivoting member. The bar includes guide rollers positionedat both edges of the conveyor belt for lateral control of the belt.

In another embodiment, a pivoting member is provided for use in aconveyor belt alignment system for a conveyor having a conveyor belttrained over rollers on a conveyor frame, the system having two suchpivoting members, the pivoting members being configured for supportingtracking rollers at corresponding tracking roller shaft ends. Eachpivoting member includes a bushing housing defining a bushing chamber, abushing block pivotally mounted in said bushing chamber for freerotation about a vertical axis, the bushing block defining a bore, abushing member fixed in the bore of the bushing block and configured foraccommodating one of the tracking shaft ends for pivoting actionrelative to the bushing housing.

In still another embodiment, an alignment system for a conveyor having aconveyor belt trained over rollers on a conveyor frame is provided,including pivoting members each mounted on a corresponding supportbracket, the pivoting members configured for supporting tracking rollersat corresponding tracking roller shaft ends, each shaft end pivotallyand non-rotatably attached to corresponding pivoting members by arotating bushing mounted in a corresponding pivoting member; and a guidecontrol bar having two ends extending laterally outside of the conveyorframe and being pivotally connected at each end to a correspondingtorque arm that is located laterally outside of conveyor frame andconnected to said corresponding pivoting member. The bar includes guiderollers, each adjustably positioned in a corresponding aperture on endsof the guide control bar for lateral control of the belt. Each pivotingmember is pivotable about an axis transverse to a longitudinal axisdefined by the tracking roller shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a conveyor belt equipped with the present beltalignment system;

FIG. 2 is a top view of the conveyor belt of FIG. 1;

FIG. 3 is a rear view of the belt alignment system of FIG. 1;

FIG. 4 is an end view of the present belt alignment system;

FIG. 5 is a vertical section taken along the line 5-5 of FIG. 4 and inthe direction indicated generally;

FIG. 6 is a vertical section taken along the line 6-6 of FIG. 5 and inthe direction indicated generally;

FIG. 7 is an exploded elevational view of the present alignment system;

FIG. 8 is a top view of the present alignment system mounted on aworking flight of the conveyor belt; and

FIG. 9 is a front elevation of the system of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, the present conveyor belt alignment system,generally designated 10, is intended for use in combination with aconveyor, generally designated 12 of the type having an elongatedflexible endless belt 14 trained over a head roller and a tail roller(not shown), the head roller being rotatably powered by a conveyordrive. A typical conveyor 12 will include a relatively rigid conveyorframe 16 holding the rollers in substantially parallel orientation forrotation about parallel rotational axes. The conveyor belt 14 is trainedabout the head and tail rollers, thereby forming a working or troughingflight and a return flight. It is noted that the width and length of thebelt 14 may vary. Also, it is contemplated that the belt 14 may beplanar or flat, as well as cupped to retain particulate matter,particularly on the troughing flight as seen in phantom in FIGS. 1 and9. The present system 10 may be mounted either on flat or cuppedportions of the belt 14.

The present alignment system 10 includes two pivoting members 18, 20which are preferably mounted on a support bracket 22 on either theworking flight side or the return flight side of the conveyor belt 14.It is noted that numerous such support brackets 22 can be used,depending on the overall length of the conveyor belt 14. It is alsocontemplated as seen in FIG. 9, that the support brackets 22 areeliminated.

The alignment system 10 further includes castellated tracking rollers 24mounted on a shaft 26 (FIG. 5) having a pair of shaft ends 28. It isnoted that the shaft 26 need not extend continuously through thecorresponding roller 24 but may be provided in shaft segments, that therollers 28 could also be regular steel or rubber lagged rollers, withthe latter preferred, and that they do not have to be castellated in allinstances. Each shaft end 28 is accommodated in a rotating bushing 30.

More specifically, and referring to FIGS. 2-7, each pivoting member 18,20 is generally “L”-shaped, including a torque arm 32 fixed normallyadjacent to an end of a bushing housing 34. Each torque arm 32 islocated laterally outside of the conveyor frame 16 and is connected to acorresponding pivoting member 18, 20. The bushing housing 34 ispreferably polygonal and the shape may vary, but in the preferredembodiment is square in cross-section (FIGS. 6 and 7), and defines abushing chamber 36. While other materials are contemplated, thepreferred bushing housing 34 is 3 inch square HSS tubing. It iscontemplated that the size of the tubing will vary with belt size. Anopen end 38 of the bushing chamber 36 located opposite the torque arm 32forms the location for the rotating bushing 30.

Referring now to FIGS. 5-7, the rotating bushing 30 includes a block 40dimensioned to be freely rotatable about a vertical axis defined bypivot pins 42 engaged in upper and lower walls 44, 46 of the bushinghousing 34. The block 40 includes a central bore 48 provided with acircular bushing member 50. In the preferred embodiment, a central bore51 of the bushing member 50 is configured for individually, pivotallyand non-rotatably accommodating at least one of the roller shaft ends 28or an optional shaft adapter 52. As is known in the art, the shaftadapter 52 has a shaft engagement end 54 for receiving the shaft end 28,and an opposite end 56 having the same dimensions as the shaft end forengaging the bushing 30.

It is preferred that the bushing member 50 is an Oil Lite bushing, withan opening 58 at least one end for receiving one of the pivot pins 42,which are hollow and are each preferably provided with a lubricatingfitting 60, such as the conventional Zerk fitting. As such, lubricantsuch as oil or grease may be injected into the fitting 60 forlubricating the bushing 30 and the shaft end 28. In the preferredembodiment, both pins 42 are provided with lubricating fittings 60.Also, as seen in FIG. 7, one of the pins 42U is provided with longerlength so that it extends transversely through the block 40 and thebushing member 50 for engaging a flat spot 61 (FIG. 6 shown in phantom)on the shaft end 28 for preventing rotation of the shaft end relative tothe bushing member 50. However, the shaft end 28 still pivots with theblock 40 relative to the bushing housing 34 about a pivot axis definedby the pins 42.

Another feature of the present system 10 is that the pivot pins 42 areeach preferably provided with a tubular pin bushing 62 for facilitatingthe rotation of the block 40 relative to the bushing housing 34. Whilethe material may vary to suit the situation, the pin bushing 62 ispreferably made of the same Oil Lite material as is the bushing member50. Thus, upon assembly and proper lubrication, the present rotatingbushing 30 readily accommodates the full degree of deflection of theshaft 26 having the tracking rollers 24 and the shaft ends 28 tomaintain desired belt alignment as will be described below.

Referring now to FIG. 5, each pivot member 18, 20 is mounted on acorresponding support bracket 22 by a pivot housing 63. The supportbracket 22 is in turn mounted to the conveyor frame 16, either on theworking flight or the return flight of the conveyor belt 14. In FIGS.1-3 and 5, the support bracket 22 is shown mounted to the conveyor frame16 so that the present alignment system 10 is associated with the returnflight.

Returning now to FIGS. 2-4, a free end 64 of each torque arm 32 oppositethe bushing housing 34 is pivotally attached at a pivot point such as abolt 66 to a corresponding end 68 of a guide control bar 70 having endsextending laterally past or outside the conveyor frame 16. Attached tothe guide control bar 70 are two spaced, freely rotating guide rollers72 (FIGS. 2 and 4) positioned for periodically engaging correspondingedges 74 of the conveyor belt 14.

The guide or tracking control bar 70 activates the pivoting mechanismprovided by the pivoting members 18, 20, through the torque arms 32.Unlike tracking rollers used in combination with conventional conveyorbelt applications, the present alignment system 10 provides for theconveyor belt 14 crossing tracking rollers before the belt reaches theguide rollers 72, thereby ensuring that the guide rollers adjust thecorrect belt path rather than the mistracking path.

In operation, as the belt 14 travels along the conveyor 12, the guiderollers 72 generally follow the lateral movement of the belt, therebycontinuously monitoring and controlling the belt alignment and axis. Itis contemplated that when the belt 14 is properly aligned, the guiderollers 72 may not be engaged by the belt edges 74. As the belt 14drifts in one lateral direction, for example the right as seen at thearrow B in FIG. 2, the right guide roller 72R will begin to rotate andalso move right on the control bar 70, seen by the arrow B′, causing theadjacent pivot member 18 to rotate clockwise as seen in FIG. 2 about itspivot axis defined by a mounting pin 76 (best seen in FIG. 5) as shownby arrow B′″. The mounting pin 76 is provided with a bearing 78 forfacilitating relative rotation of the pivot housing 63 connected to thebushing housing 34. Thus, the pivot housing 63 and the bushing housing34 move together. The guide control bar 70 is thus connected at each endto the shaft end 28 through three pivot points, 42, 76 and 66.

This movement causes the bushing housing 34 to also rotate clockwise,causing the corresponding shaft end 28 to move upward at arrow B″″ asseen in FIG. 2. Such shaft deflection will be accommodated by thebushing 30 in the opposite pivot member 20, which will accommodate themovement of the opposite shaft end 28 in the opposite direction(downward as seen in FIG. 2). In addition, this deflection of the shaftend 28, and the subsequent angled orientation of the tracking rollers24, will cause the belt 14 to move back to its desired centeredposition. As the belt 14 moves back to the centered position, theopposite edge 74 may eventually engage the opposite guide roller 72L.

Referring now to FIGS. 8 and 9, an alternate embodiment of the presentsystem 10 is generally designated 80. Components shared with the system10 are designated with identical reference numbers. The system 80 ismounted on an upper surface of the conveyor frame 16 to be associatedwith the working flight of the belt 14 (shown in phantom in FIG. 9).Thus, the system 80 is mounted beneath the belt 14. A structuraldifference of the system 80 is that the guide rollers 72 are mounted onangled extensions 82 which are in turn mounted to the guide control bar70 so that the rollers are in operational relationship to edges 74 ofthe belt 14. As is known in the art, the belt 14 is supported in itscupped or troughed shape by angled rollers 84 as well as generallyhorizontally aligned rollers 86 (FIG. 1).

Thus, the system 10 operates with a series of freely pivotable points66, 76 and 42. By providing the bushing member 50 in the freelypivotable bushing block 40, the present system 10 provides a greaterdegree of accommodation of shaft deflection compared to prior art units.Such greater degree of deflection accommodation facilitates conveyoroperation and prolongs the operational life of both the alignment system10 and the conveyor 12.

On the return flight side of the conveyor belt, the support bracket 22and pivoting members 18, 20 are mounted onto the frame 16, also referredto as a conveyor stringer. This in turn will prevent any build upmaterial from jamming the pivoting members 18, 20 and the trackingrollers 24. It will be appreciated that the present system 10 can beinstalled in a new conveyor or as a retrofit unit to existing conveyors.

While a particular embodiment of the present conveyor alignment systemwith rotary bushing has been shown and described, it will be appreciatedby those skilled in the art that changes and modifications may be madethereto without departing from the invention in its broader aspects andas set forth in the following claims.

1. An alignment system for a conveyor having a conveyor belt trainedover rollers on a conveyor frame, the system comprising: pivotingmembers each mounted on a corresponding support bracket, said pivotingmembers configured for supporting tracking rollers at correspondingtracking roller shaft ends; each said shaft end pivotally andnon-rotatably attached to corresponding pivoting members by a rotatingbushing mounted in a corresponding one of each of said pivoting members;and a guide control bar having two ends and being pivotally connected ateach said end to a corresponding torque arm connected to saidcorresponding pivoting member; and said bar including guide rollerspositioned at both edges of the conveyor belt for lateral control ofsaid belt.
 2. The alignment system of claim 1 wherein said pivot memberincludes a housing defining a bushing chamber, and said bushing includesa block rotatable about a vertical axis defined by pivot pins engaged inupper and lower walls of said housing.
 3. The alignment system of claim2 wherein said block is dimensioned to freely rotate within said bushingchamber.
 4. The alignment system of claim 2 wherein said block includesa central bore provided with a bushing member.
 5. The alignment systemof claim 4 wherein said bushing member is configured for individuallyaccommodating at least one of a roller shaft and a shaft adapter.
 6. Thealignment system of claim 4 wherein said bushing member is an Oil Litebushing.
 7. The alignment system of claim 2 wherein at least one of saidpins is provided with a lubricating fitting.
 8. The alignment system ofclaim 7 wherein said lubricating fitting is a Zerk fitting.
 9. Thealignment system of claim 2 wherein at least one of said pins isprovided with a pin bushing.
 10. The alignment system of claim 4 whereinat least one of said pins is long enough to project through said bushingmember to engage a flat spot on a corresponding one of said shaft endsfor preventing rotation of the shaft end in the bushing.
 11. Thealignment system of claim 1 wherein said pivot member is generally“L”-shaped, including a housing defining a bushing chamber orientednormally to a torque arm.
 12. The alignment system according to claim 1wherein the support brackets are positioned on one of a working flightside or return flight side of the conveyor belt.
 13. The alignmentsystem according to claim 12 wherein when the support brackets arepositioned on the return flight side of the conveyor belt said belt mayride on one of the top and beneath tracking rollers.
 14. The alignmentsystem according to claim 1 wherein said tracking rollers arecastellated.
 15. A pivoting member for use in a conveyor belt alignmentsystem for a conveyor having a conveyor belt trained over rollers on aconveyor frame, the system having two such pivoting members, thepivoting members being configured for supporting tracking rollers atcorresponding tracking roller shaft ends, said pivoting membercomprising: a bushing housing defining a bushing chamber; a bushingblock pivotally mounted in said bushing chamber for free rotation abouta vertical axis, said bushing block defining a bore; and a bushingmember fixed in said bore of said bushing block and configured foraccommodating one of said tracking shaft ends for pivoting actionrelative to said bushing housing.
 16. The pivoting member of claim 15wherein said bushing block pivots relative to said bushing housing by apair of pivot pins passing through said housing into said block.
 17. Thepivoting member of claim 16 wherein at least one of said pins isprovided with a pin bushing.
 18. The pivot member of claim 16 wherein atleast one of said pins is provided with a sufficient length to projecttransversely through said bushing member to engage a flat spot on acorresponding one of said shaft ends for preventing rotation of saidshaft end in said bushing.
 19. An alignment system for a conveyor havinga conveyor belt trained over rollers on a conveyor frame, the systemcomprising: pivoting members each mounted on a corresponding supportbracket, said pivoting members configured for supporting trackingrollers at corresponding tracking roller shaft ends; each said shaft endpivotally and non-rotatably attached to corresponding pivoting membersby a rotating bushing mounted in a corresponding one of each of saidpivoting members; a guide control bar having two ends extendinglaterally outside of said conveyor frame and being pivotally connectedat each said end to a corresponding torque arm that is located laterallyoutside of said conveyor frame and connected to said correspondingpivoting member; said bar including guide rollers, each adjustablypositioned in a corresponding aperture on ends of the guide control barfor lateral control of said belt; and wherein said pivoting member ispivotable about an axis transverse to a longitudinal axis defined bysaid tracking roller shaft.
 20. The alignment system of claim 19 whereinsaid guide control bar is connected at each end to said correspondingtracking roller shaft end through three pivot points.